This invention is related to the laser welding method of steel plate and steel ingot, in which the efficiency such as lessened laser power, reduction of laser irradiation time, distortion prevention of the weldment and high welding rigidity is maximized in comparision with the prior art. The prior laser welding methods are classified into two kinds according to the thickness of the steel.
As shown in FIG. 7, when the steel plates less than 1 mm thick are welded, two weldments (1) (2) are laid to put one upon the other in the shape of being welded and then laser beam is irradiated for a certain time only on the first weldment (1) (the upper one) with focussing on the second weldment (2) to weld the both weldments, i.e. steel plates.
When the steel ingots more than 1 mm thick are welded, as shown in FIG. 8, two weldments (4,5) are laid to put one upon the other in the shape of being welded and then high laser beam (3) is irradiated only on the edge along the junction face of the two weldments, i.e., steel ingots.
However in the laser welding of steel ingot in the prior art, the output of laser must be large, the irradiation time of laser is uneconomically long, and in the laser welding of steel plate, the thin steel plate is distorted on account of thermal expansion on the welded part, further more the welded part is cracked easily by the outside shock on account of low rigidity.